This exploratory/developmental application requests funds to design and pilot test an Internet-based HIV/STI prevention program for ethnically diverse young MSM (YMSM;ages 18-24) receiving HIV testing. Rising rates of sexual risk taking, HIV/AIDS, and STIs among YMSM, combined with the lack of inclusion of MSM-relevant content in school based sex education, underscores the need for innovative prevention targeted at this population. Testing negative for HIV has been linked to increased rates of sexual risk taking among MSM and CDC recommended client- Centered counseling (CCC) is not always being rigorously conducted in testing sex partners and health information in this population. We will use the proven ADDIE approach to E-learning production to develop a highly-interactive and tailored online intervention. During the Analysis stage we will identify key content to include from two empirically supported HIV prevention programs originally developed for MSM (The AIDS Community Demonstration Project and The Behavioral Intervention to Reduce AIDS Risk Activities). We will also include a unique affect regulation skills training component for Project BALANCE, an innovative HIV prevention intervention developed for young adults with mental health problems. We will work closely with an expert Advisory Board to develop the intervention, drawing on the Tran theoretical Model of behavioral change (TTM) and our model interventions. In the Design stage we will develop a blueprint for the intervention and will then conduct qualitative interviews with a least 18 ethnically diverse YMSMs to get their feedback on the intervention content, style and cultural acceptability. During the Development stage we will incorporate this feedback into the construction of the online modules and conduct usability and acceptability testing with 6 ethnically diverse YMSM. After we Implement the modules comes the Evaluation stage, when we will test the final program in a pilot randomized controlled trail (RCT) in a sample of 80 ethnically diverse YMSM who were recently tested for HIV in the clinic of our community partner. The control group will receive CCC and online HIV information-only content. The experimental group will receive CCC and the highly-interactive and tailored web-based HIV/STI prevention modules. Participants will complete baseline, post-intervention, 6 week, and 12 week assessments to evaluate tracking and retention strategies, and preliminary treatment effects. Data analyses will (a) evaluate change in HIV risk behaviors as a function of intervention participation, and (b) determine the effect size of intervention impact on the outcomes variables. We will use the effect size to determine the sample size needed for a more validated, Interned-based, HIV prevention program to reduce health risk behavior among highly-vulnerable YMSM who were recently tested for HIV.